Generally, my humble fantasy preference is to not use brakes except softly to slow the car, along with downshifting, to threshold corner entry speed as brake markers are passed before a turn, counting down in rhythm with the downshifts 3-2-1 to turn-in at zero, which is where the throttle is closed, the diff goes into coast, the car rotates, throttle is applied and the suspension is locked on a vector that crosses over a point of choice at exit, while countersteer fixes the front on the default line of least resistance against the track camber thru the turn.

Others have their own ideas.

When the diff goes into coast the rear suspension relaxes and the mass at the back, no longer held in place by engine torque, heads out on its own vector at the sum of a tangent and the line of travel.

A driver can target a landmark alongside the track on the outside of a turn and by going off throttle set the rear's vector toward the target with the same certain confident precision that is required to get the car around the corner.

The rear's off-line attempt at escape is limited by its connection to the rest of the car and the tires, so all it can do is begin to "rotate" the car around its CoG and load the tire patch in an effort to relieve itself of a force with no place else to go.

This applies downward pressure at the tire patch on the outside rear which increases grip as loading approaches the maximum possible before any more excess force has no choice but to find another place to be.

From the driver's POV the best place for excess force to go is back into the springs to propel the car's sprung weight forward, which is what it will do when the car's suspension is accurately and correctly tuned.

As soon as rotation begins the front is steered into the track camber and hopefully, if toe bars and shocks are dialed-in, all four tires will settle at maximum lateral load, enjoy the same angle of attack, (neutral steering), and the car will easily negotiate the turn relying only on fully accelerating throttle from the pre-apex instant of coming back out of coast.

Dave is quoted at saying a 45/85/1 diff setting is realistic. That may be in the real car but not in GPL. When talking about the original Papy physics we're talking about grip that's less than the real car. Proven by driving the Lotus 49 in iRacing and comparing it to the GPL version. Both developed by the same guy.

So, what happens when a noob to GPL use that 45/85/1 diff. He'll spin out in every turn. If he RF brakes it will be worse.

Early on we discovered that if we give some throttle with the braking we could use the 45/85/1 diff setting. By using throttle with braking we can lock and unlock the diff by the throttle setting. Of course, this has to be done bt LF braking. So, we had to use an unrealistic driving method to 67 F1 cars to use a realistic diff setting because the car doesn't have realistic grip.

It's much easier to use a 45/85/1 diff in the 65 mod because the cars have much more grip than the 67 F1 cars.

So, what do we have to do if we want to drive with a realistic method. Which means RF braking and no throttle with braking. We have to use an unrealistic diff setting to compensate for the unrealistic grip.

You make a choice on how you want to drive GPL and then use the diff setting that works for you. Nothing is black and white in simulations. Use what works for you.

Interests:Cycling: Road and Off Road.
Driving well and safely.
Growing Vegetables.

Sim interest:GPL

Posted Jan 10 2019 - 03:20 PM

Pete,"Dave is quoted at saying a 45/85/1 diff setting is realistic." As I have learned recently from another thread, F1 cars of the 1960's did not have limited-slip differentials as modeled in GPL; so there is nothing realistic about it at all. Or do the figures relate to other types of diff?

Pete,"Dave is quoted at saying a 45/85/1 diff setting is realistic." As I have learned recently from another thread, F1 cars of the 1960's did not have limited-slip differentials as modeled in GPL; so there is nothing realistic about it at all.

Agree. For me 'realistic' diff setting is those that will make Salisbury LSD modeled in GPL behave more like Cam and Pawl LSD that were used on cars of the 60's. And I think it is 30/85/6 setting...

Did somebody try different diffs setups in the 67x mod? In general I find that mod as very (and I think correctly) responsive to different setup settings.
Also, the grip was (imho) improved from the original 67's, with more grip at slow speeds and less at higher ones. And I guess it should allow more realistic setups too.

When I first started to drive GPL I worked up to using a 45/85/1 diff and all my PB's were set that way. I was a LF braker and used throttle with the braking. It was an easy way to drive and it's no wonder aliens like to drive that way.

After a while I wanted to drive in a more realistic 67 style of driving. I started to use RF braking and could no longer use the 45/85/1 diff. I tried but I was too inconsistent and had spins. I pride myself in never spinning out, so I needed to make changes. I went to what Greger used in his GH1 setups. 85/45/1. It was much easier to drive and I stayed with it while making changes in the setup to help it turn better but staying with the 85/45/1 diff. I finally got to the point of matching my PB times and even passing some of them.

My point is don't use a diff setting that you can't drive. Use a setting that's comfortable to drive and doesn't make to spin off. No matter how fast a setup is if you can't stay on the track you'll be slower at the end of a race.

I guess I am strange. I only play 1965 mod for now (still learning the craft). Brabham BT11 only. Mostly default setup, I only slowly lowered brake bias to 53% and changed the diff from 60/30/2 to 30/60/2 - and then again to 30/45/2 to avoid too much oversteer when braking.

Preference for specific ratios does seem to have implications about how the diff is used.
Or if its capabilities are used to their full extent or to what extent?

One important use of the diff is to cause the car to rotate as it transitions between throttle on-off-on while the car is turning.

That is a capability that can be taken advantage of to improve control and reduce lap times. We know it is an important capability because the whole host of experts has for years been telling us that, (or trying to).

Regardless of their diff setting, when newbies ask why does the car spin out when I let off the gas in a turn the first answer should be, "It is supposed to. Countersteer and floor it! Get used to that."

As mcmirande's comment implies, tweaking toe settings in particular aligns car to diff rotation in compliment to or in spite of other settings.

Looks like I've been doing my setups all wrong 👋 My philosophy was to set my diff settings for different cars, mods and even set differently for different tracks. I thought the diff was an ongoing adjustable setting, with flexibility. I didn't realise that you found a setting to your driving style and pretty much kept it for all mods, cars and tracks.

Would you say that the key is to use your diff setting as your base. Then adjust the other car settings, on top of that 🤔